Actually, I would hesitate - strongly - in calling deification a 'divine act' in any unqualified way. The process of deification is one that intrinsically involves both God and man in symphonia. As such, it is properly an action of this struggle. ... Deification is part-and-parcel of the authentic ascetical struggle, and so I would rather stand by calling it an 'ascetical act'. All ascetical purification is always the working of divine grace, working specifically in symphony with the active repentance of the human person. Part of the challenge that articulation of deified life has traditionally faced has been the tendency to divorce it from its authentic ascetical context -- either by claiming it a wholly divine act (which is neither ascetical, nor truly deification; it is rather manipulation), or by claiming it is a wholly human act (which again is not ascetical, as ascesis is never distinct from the active working of God's grace).
Going back to the initial context of defining 'Church', it still seems to me quite inaccurate to attempt to identify it with deification, not least because deification is not a thing, but at attribute of act and ascetical transformation. In your most recent post, Richard, you note that your intention in that earlier comment was to emphasise that 'the Church - being Christ’s Body of which we are a part [...] - is made up of us who by being united with Christ are also deified.' This is surely a good point to emphasise. But the patristic language of deification is so regularly misunderstood and misused that special attention needs to be paid with it; hence my response. Deification is, patristically defined, an anthropological doctrine that forms part of the Christian articulation of human nature and human existence. The Church is not to be described in terms of human existence itself, but as the communion in Christ whereby this human existence is realised and restored.
Regarding the title 'angel' with respect of Christ ... Yes, this harks back to the distinction I made in my earlier post: namely that 'angel' is used in different ways in the Church. As a category of being, it is clearly inapplicable to Christ (as Fr David noted initially); as a title meaning 'messenger', it has a certain applicability to Christ -- as a few (though not many) of the fathers employ it (the most obvious to me is Justin, as I noted, who focused on it rather directly; though you also helpfully provided another example, which I believe is from St Gregory Palamas -- though I couldn't quite make clear sense of the attribution section of that paragraph in your post). So in these comments from your most recent post, I can certainly see that this is something recognised all around (which I trust will allay Fr David's concerns, expressed in his initial response). That said, I still believe the following to be problematic: While I do think I understand your intention in this, Richard, it still seems to conflate important terms and ideas. The scriptures (e.g. the prophet Malachi) never speak of 'the angel' who then 'becomes incarnate'. Rather, the incarnate Christ is declared to be angel - messenger. This is, admittedly, a nuanced distinction, yet it is extremely critical. The Son is not 'angel' who becomes incarnate; in other words, he is not 'messenger' in this manner before the incarnation, such that the incarnation becomes an act or phase of the Son's/Angel's existence. Rather, when the Son takes flesh and becomes man, this incarnation is the very substance of his 'message' - the full revelation of the Father. The Angel of the Lord does not become incarnate; the eternal Son becomes, in the incarnation, the angel/Angel (the capitalisation is irrelevant) of the Father's redemption: the very messenger of the glory he is himself as the Father's eternal Son.